1. Field of the Invention
The present invention relates to a Ram airbreathing high power laser generally operable in the Mach 3 to Mach 6 regime.
2. Description of the Prior Art
Gas dynamic lasers use the principal of thermodynamically expanding a mixture of hot selected gases which are subsequently introduced into an optical resonant cavity where a population inversion in a species of the gases, typically CO.sub.2, produces lasing action.
The open cycle gas dynamic laser (GDL) typically uses large quantities of stored gas for the laser working medium. A large fraction of laser weight is associated with the storage and conditioning of this gas, which is exhausted to the atmosphere after passing through the laser cavity. A large reduction in system weight is possible by replacing the stored gases (primarily N.sub.2) with air (approximately 78% N.sub.2 and approximately 21% O.sub.2) and the combustion of appropriate fuels, such as benzene, to provide the proper lasant gas composition, temperature and pressure.
U.S. Pat. No. 4,013,976 discloses a GDL wherein combustion or compressor gases are diverted from the normal flow path through a gas turbine engine into an auxiliary flow path, the composition of the gases subsequently being modified to provide increased laser power.
The GDL of the type described in the aforementioned patent can be readily used on aircraft, the resultant laser beam being compatible primarily with relatively low to moderate power applications, due to the impact of the diverted gases on airplane performance, unless a dedicated engine is assumed. Although such an airborne GDL is relatively altitude and airspeed independent, its operating capability is generally better suited to Mach regimes less than about 3 where turbojet and turbofan engines typically operate.
Ram airbreathing lasers (RAL) operating in the Mach 3 to Mach 6 regime have been previously studied (Articles by M. J. Brunner, "Ram Airbreathing Laser Performance" AIAA paper 74-1139, 10th Propulsion Conference, San Diego, CA, Oct. 21-23, 1974 and "Ram Airbreathing Laser," General Electric Co., ARL TR 74-0036, Fluid Dynamic Facilities Research Laboratory/LF, Aerospace Research Facility, WPAFB, Ohio, May 1974). In particular, laboratory demonstrations have been performed to confirm the physics, and demonstration components have shown performance factors suitable for prototype development. Also, computer studies have been made of both the laser kinetics and operational applications. RAL's use air initially heated by ram compression in the engine inlet duct, the heated air being diverted to a mixing chamber wherein hydrocarbon fuel may be burned. Some RAL's, especially at high mach numbers, may not require an additive. Suitable thermodymamic expansion of the resultant gases produce a population inversion in the CO.sub.2 species which then can be utilized to produce a laser beam. The high air mass flow rates possible and the high temperature gas resulting from the ram compression and the burning in the combustion chamber can result in lasers capable of producing a wide range of beam energies (low to high) which can be utilized in a variety of military and non-military applications.
Previously RAL's have been configured as generally self-contained systems. However, it would be desirable in a mobile vehicle, such as an aircraft or a missile, to integrate airvehicle and laser functions, such as pre-combustion functions (specifically those related to the air induction system) in a more efficient and cost effective manner than heretofore available.